Injection ports are placed beneath the skin of a body for injecting fluids into the body, such as for infusing medication, blood draws, and many other applications, including adjustable gastric bands. Since the early 1980s, adjustable gastric bands have provided an effective alternative to gastric bypass and other irreversible surgical weight loss treatments for the morbidly obese. The gastric band is wrapped around an upper portion of the patient's stomach, forming a stoma that restricts food passing from an upper portion to a lower portion of the stomach. When the stoma is of the appropriate size, food held in the upper portion of the stomach provides a feeling of fullness that discourages overeating. However, initial maladjustment or a change in the stomach over time may lead to a stoma of an inappropriate size, warranting an adjustment of the gastric band. Otherwise, the patient may suffer vomiting attacks and discomfort when the stoma is too small to reasonably pass food. At the other extreme, the stoma may be too large and thus fail to slow food moving from the upper portion of the stomach, defeating the purpose altogether for the gastric band.
In addition to a latched position to set the outer diameter of the gastric band, adjustability of gastric bands is generally achieved with an inwardly directed inflatable balloon, similar to a blood pressure cuff, into which fluid, such as saline, is injected through a fluid injection port to achieve a desired diameter. Since adjustable gastric bands may remain in the patient for long periods of time, the fluid injection port is typically installed subcutaneously to avoid infection, for instance in front of the sternum. Adjusting the amount of fluid in the adjustable gastric band is achieved by inserting a Huber needle through the skin into a silicon of the injection port. Once the needle is removed, the septum seals against the hole by virtue of compressive load generated by the septum. A flexible conduit communicates between the injection port and the adjustable gastric band.
The traditional surgical technique for securing a fluid injection port developed for vascular uses has been applying sutures through a series of holes spaced about a peripheral base flange. While generally effective, suturing often proves to be difficult and time consuming, even more so with adjustable gastric band which are intended for the morbidly obese. A significant thickness of fat tissue may underlie the skin, causing difficulties as the surgeon attempts to apply sutures to deeply recessed tissues (e.g., 5-10 cm) to secure the port, often requiring 10-15 minutes to complete. Further, if the injection port is not sutured properly, the port may flip over, making subsequent injections difficult or impossible.
Recently, a surgical stapler has been described in a German patent application No. 197 51 791.9 to Pier wherein a hat-shaped injection port includes tangentially aligned linear grooves spaced around its perimeter. A pair of holes in each linear groove receives a traditional bent wire staple. A stapler holds the staples in place and has downwardly moving forming member that presses upon the shoulders of each staple. Due to the position of the holes in the linear groove, pointed ends of the staple are deformed inwardly to grip underlying tissue.
This Pier stapler thus attaches the staples through a deformation that may prove difficult to release should the initial placement be undesirable or removal of the gastric band be appropriate. Further, because the device must permanently deform a multiplicity of stainless steel or titanium staples, a more complicated mechanism is required to provide the surgeon with enough mechanical advantage to form the staples easily. The Pier injection port also requires a custom stapler handle that is not useful for any other purpose, which may be an undesirable expense for surgeons who do not perform numerous placements of the Pier injection port.
While a custom stapler for an injection port may have advantages over suturing, such as the time required to accomplish the attachment, it is believed that other approaches to attaching an injection port may have additional advantages or features not provided by traditional suturing or a stapler using bent wire staples.
Consequently, a significant need exists for a fluid injection port suitable for subcutaneous attachment that is quickly attachable yet is secure over a long period of time.